A cyclic process of peptide design, peptide synthesis and peptide conformation study is used to refine methods of determining oligopeptide conformation in solution and predicting it from amino acid sequence. The principal technique for conformation study is high resolution nuclear magnetic resonance, coupled with model building and empirical calculation of conformation. Correlations are made with optical (infrared, CD) data, crystallographic results, and chemical reactivity. The peptides to be used in this work are chiefly (a) synthetic cyclic oligopeptides, (b) linear oligopeptides, designed to fold into strongly preferred conformations other than helical, (c) isotopically labeled peptides obtained by cleavage of the algal protein phycocyanin, and (d) synthetic analogs of peptide hormones. Transitions among stable conformations of some of these peptides are under study. BIBLIOGRAPHIC REFERENCES: K.D. Kopple and A. Go, Studies of Peptide Conformation, Backbone Folding of Tetrapeptide Derivatives in Methanol and Water, Biopolymers, 15, 1701-1715 (1976). D.R. Pilipauskas and K.D. Kopple, Cyclic Oligomers of 4-Aminopentanoic Acid, Tetrahedron, 32, 2245-2247 (1976).